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Combined Science GCSE 1-9 > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What is the nucleus?

A

The subcellular structure in an animal or plant cell which contains genetic material (in the form of chromosomes) and controls the activities of the cell.

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2
Q

What are mitochondria?

A

Subcellular structures in plant and animal cells that provide energy by carrying out respiration

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3
Q

What are ribosomes?

A

Subcellular structures in plant and animal cells that carry out protein synthesis.

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4
Q

What is a cytoplasm?

A

A subcellular structure in plant and animal cells where most of the chemical reactions take place. It contains enzymes that control these chemical reactions.

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5
Q

What is a cell membrane?

A

A subcellular structure that holds the cell together and controls the movement of substances in and out of the cell

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6
Q

What are chloroplasts?

A

Subcellular structure in plants, where photosynthesis occurs, which makes food for the plant. They contain chlorophyll, which absorbs the light needed for photosynthesis.

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7
Q

What is a permanent vacuole?

A

A subcellular structure in a plant cell that is filled with cell sap to help keep the cell turgid.

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8
Q

What is a cellulose cell wall?

A

A subcellular structure in a plant cell that gives strength to the cell and supports the plant

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9
Q

What are plasmids?

A

Extra genetic material (small rings of DNA) in a bacterial cell

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10
Q

What is a prokaryote?

A

Organisms made up of a prokaryotic cell (it’s a single celled organism)

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11
Q

What are eukaryotes?

A

Organisms made up of eukaryotic cells.

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12
Q

What is a eukaryotic cell?

A

Complex cells (all animal and plant cells are eukaryotic)

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13
Q

What is a prokaryotic cell?

A

A cell that is smaller and simpler than eukaryotic cells, e.g. bacteria

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14
Q

What are subcellular structures?

A

The different parts of a cell

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15
Q

What subcellular structures are in most animal cells?

A

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

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16
Q

What subcellular structures are in plant cells?

A

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, cell wall, permanent vacuole, chloroplasts.

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17
Q

What subcellular structures are in most bacterial cells?

A

Cell membrane, cell wall, cytoplasm, single circular strand of DNA that floats freely in the cytoplasm (they DONT have a true nucleus), they might contain plasmids. They DONT have chloroplasts or mitochondria.

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18
Q

Describe what light microscopes do.

A

They use light and lenses to form an image of a specimen and magnify it. They let us see individual cells and large subcellular structures, like nuclei.

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19
Q

Describe what electron microscopes do.

A

They use electrons instead of light to form an image. They have a much higher magnification than light microscopes. They also have a higher resolution. Electron microscopes allow us to see much smaller things in more detail, like the internal structure of mitochondria and chloroplasts. They even let us see tiny things like ribosomes and plasmids.

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20
Q

What is resolution?

A

Resolution is the ability to distinguish between 2 points, so a higher resolution gives a sharper image.

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21
Q

What is the formula for calculating the magnification of an image?

A

Magnification = image size/real size

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22
Q

What is standard form?

A

Where you change very big or very small numbers with lots of zeros into something more manageable. E.g 0.017 can be written as 1.7 x 10-².

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23
Q

How do you do standard form?

A

You move the decimal point to the left or right, uniltil the number becomes somewhere between 1 and 10. The number of places the decimal point moves is then represented by a power of 10 - this is positive if the decimal point’s moved to the left, and negative if it’s moved to the right.

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24
Q

What is a slide (for a microscope)?

A

A strip of clear glass or plastic onto which the specimen is mounted.

25
Q

How do you prepare a slide to view onion cells?

A

1) add a drop of water to the middle of a clean slide
2) cut up an onion and separate it out into layers. Use tweezers to peel off some epidermal tissue from the bottom of one of the layers.
3) using tweezers place the epidermal tissue into the water on the slide.
4) add a drop of iodine solution, to highlight objects in the cell.
5) place a cover slip (a square of thin, transparent glass or plastic) on top. To do this, stand the cover slip upright on the slide, next to the water droplet. Then carefully tilt and lower it so it covers the specimen. Try not to get any air bubbles under there - they’ll obstruct your view of the specimen.

26
Q

What is iodine solution? Why is it used?

A

A stain. Stains are used to highlight objects in a cell by adding colour to them.

27
Q

How do you use a light microscope?

A

1) clip the slide you’ve prepared onto the stage.
2) select the lowest powered objective lens (the one that produces the lowest magnification)
3) use the coarse adjustment knob to move the stage up to jsut below the objective lens.
4) look down the eyepiece. Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus.
5) adjust the focus with the fine adjustment knob, until you get a clear image of what’s on the slide.
6) if you need to see the slidw with greater magnification, swap to a higher-powered objective lens and refocus.

28
Q

How do you draw your observations?

A

1) draw what you see under the microscope using a pencil with a sharp point.
2) make sure your drawing takes up at least half of the space available and that it is drawn with clear, unbroken lines.
3) there shouldn’t be any colouring or shading.
4) if you are drawing cells, the subcellular structures should be drawn in proportion.
5) remember to include a title of what you were observing and write down the magnification that it was observed under.
6) label the important features of your drawing (e.g nucleus, chloroplasts), using straight uncrossed lines.

29
Q

When does most differentiation occur?

A

As the organism develops. In most animal cells, the ability to differentiate is lost at an early stage, after they become specialised. However, lots of plant cells don’t ever lose this ability.

30
Q

What are the cells that differentiate in mature animals mainly used for?

A

Repairing and replacing cells, such as skin or blood cells.

31
Q

What are undifferentiated cells called?

A

Stem cells

32
Q

Specialised cell example: sperm cell. What is its function?

A

The function of a sperm is to get male DNA to the female DNA. It has a long tail and streamlined head to help it swim to the egg. There are a lot of mitochondria in the cell to provide the energy needed. It also carried enzymes in its head to defeat through the egg cell membrane.

33
Q

Specialised cell example: nerve cells. What are their function?

A

The function of nerve cells is to carry electrical signals from one part of the body to another. These cells are long (to cover more distance) and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.

34
Q

Specialised cells example: muscle cells. What is their function?

A

The function of a muscle cell is to contract quickly. These cells are long (so they have space to contract) and contain lord of mitochondria to generate the energy needed to contract.

35
Q

Specialised cell example: root hair cells. What is their function?

A

Root hair cells are cells of plant roots, which grow into long “hairs” that stick out into the soul. This gives the plant a bigger surface area for absorbing water and mineral ions from. The soil.

36
Q

Specialised cells example: phloem and xylem cells. What is their function?

A

Phloem and xylem cells form phloem and xylem tubes, which transport substances such as food and water around plants. To form the tubes, the cells are long and joined end to end. Xylem cells are hollow in the centre and phloem cells have very few subcellular structures, so that stuff can flow through them.

37
Q

What are chromosomes?

A

Coiled up lengths of DNA molecules. Each chromosome carries a large number of genes. Different genes control the development of two characteristics. E.g hair colour.

38
Q

How many copies of each chromosome do bodies normally have?

A

2 copies of each chromosome -one from the organisms ‘mother’ and one from its ‘father’. So humans have two copies of chromosome 1, two copies of chromosome 2 etc.

39
Q

What is the cell cycle?

A

A series of stages in which body cells in multicellular organisms divide to produce new cells.

40
Q

What is mitosis?

A

The stage of the cell cycle when the cell divides. Multicellular organisms use mitosis to grow or replace cells that have been damaged.

41
Q

What does the end of the cell cycle result in?

A

Two new cells identical to the original cell with the same number of chromosomes.

42
Q

One main stage of the cell cycle is the growth and DNA replication. What happens in this stage?

A

1) in a cell that’s not dividing, the DNA is all spread out in long strings.
2) before it divides, the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
3) it then duplicates it’s DNA - so there’s one copy for each new cell. The DNA is copied and forms X-shaped chromosomes. Each ‘arm’ of the chromosome is an exact duplicate of the other.

43
Q

One main stage of the cell cycle is mitosis. What happens in this stage?

A

Once its contents and DNA have been copied the cell is ready for mitosis…
1) the chromosomes line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell.
2) membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells - the nucleus has divided.
3) lastly, the cytoplasm and the cell membrane divide.
The cell has now produced two new daughter cells. The daughter cells contain exactly the same DNA - they’re identical. Their DNA is also identical to the parent cell.

44
Q

What is differentiation?

A

The process by which a cell changes to become specialised for a particular job.

45
Q

What do undifferentiated cells do?

A

They can divide to produce more undifferentiated cells. They can differentiate into different types of cell, depending on what instructions hey are given.

46
Q

What are stem cells?

A

Undifferentiated cells

47
Q

Where can stem cells be found?

A

Early human embryos and bone marrow.

48
Q

What can stem cells from human embryos and bone marrow be used for?

A

They can be grown in a lab to produce genetically identical cells (clones) and made to differentiate into specialised cells to use in medicine or research.

49
Q

What examples of diseases could be cured with embryonic stem cells?

A

You could make insulin-producing cells for people with diabetes. You could make nerve cells for people paralyzed with spinal injuries.

50
Q

How could bone marrow stem cells cure diseases?

A

Replace faulty cells (get transferred from the bone marrow of s healthy person to replace faulty blood cells)

51
Q

What is therapeutic cloning?

A

Where an embryo is made to have the same genetic information as the patient. This means that the stem a produced from it would also contain the same genes so wouldn’t be rejected by the patient’s body if replacing faulty cell.

52
Q

What are the risks in using stem cells in medicine?

A

The stem cells grown in the lab could become contaminated with a virus which could get passed onto the patient so make them sicker.

53
Q

Is stem cell research legal in the UK?

A

Yes, as long as it follows strict guidelines.

54
Q

What are reasons for embryonic stem cells research?

A

~living people that are suffering should be cured before the rights of embryos.
~embroys in labs usually come from fertility clinics as they are often unwanted and will otherwise be destroyed.

55
Q

What are the resaons against embryonic stem cell research?

A

~some people believe that experimenting on potential human life is wrong
~many campaigners believe that doctors/scientists should spend more time researching other sources of stem cells, so they wouldn’t use embryos.

56
Q

Where are stem cells found in plants?

A

In the meristems (parts of the plant where growth occurs)

57
Q

What can plant stem cells be used to do?

A

Produce clones of whole plants quickly and cheaply.

58
Q

Why is it helpful to clone plants?

A

It can prevent rare species of plant from dying out.

It can be used to grow plants with desired features for farmers (e.g. disease resistance)

Combined Science GCSE 1-9 (29 decks)

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